Shockless jolting device for molding machines



Patented Dec. 12, 1950 SHOCKLESS JOLTNG DEVECE FOR MOLDNG MACHINES Hans Jakob Rothschild, Schaffhausen, Switzerland, assigner to Georg Fischer Aktengesell schaft, Schaffhausen, Switzerland Application February 10, 1949, Serial No. 75,704 n Switzerland December 9, 1948 (Cl. 22m45) 3 Claims.

This invention relates to molding machines of the jolt, squeeze and draw type in combination with shockless jolting on an air cushion. in molding machines of the above `described type an air cushion is built below the squeeze piston to act as a shock absorber during the operation of the jolt piston.

`In known control means for molding machines of the above described type, it may happen that due to minute air leaks in the control means between the jolt cylinder and the squeeze cylindex", additional air enters the space below the squeeze plunger. This may cause an ever increasing height of the air cushion, whereby the `squeeze `plunger keeps onY rising until it has reached the squeezing position; i. e. the jolting operation is prematurely interrupted.

A principal object of the invention is to provide means for building up and limiting the height of an air cushion under the squeeze piston during the operation of the jolt piston.

Another object of the invention is to provide in the jolt piston, and slideable on a hollow valve rod, a jolt valve which opens when its lower most edge rests on the squeeze piston.

Another object of the invention is to provide guiding means for the hollow valve rod in the bores of the .jolt piston and in the squeeze piston which allow for radial adjustments between the various moving parts and at the same provide an air tight axial connection.

The nature of our improvements will be bst understood as described in connection with the drawings in which they are illustrated and in which:

, Fig. l is a vertical sectional elevation of the molding machine with the necessary air conduits,

Fig. 2 shows the control valve disk and operating lever of the control valve,

Fig. 3 shows a modified and improved construction of the valve rod guide.

Fig. 1 illustrates the squeeze cylinder I in which slides a squeeze plunger 2, the bore of which serves as a guide for a jolt piston 3. On top of the molding machine table i rest the pattern or molding plate and the ask with the mold, which are not shown in Fig. 1 attached into the centre. of the bottom 'l of `the squeeze. cylinder I is the hollow valve rod S, which is closed at the upper end where the abutment I is screwed on By means of conduit 5, the lower open end o the hollow valve rod t is connected with the control valve body 8. The hollow valve rod 6 is guided in the squeeze plunger 2 in the valve rod guide 9 and in the jolt piston 3 in the valve 2 rod guide It. in the lower part of said 'hollow valve rod 6 are the openings II which in the lowermost position of said squeeze plunger 2 lead into the passages I2 directed towards the bottom of said squeeze plunger 2. Other openings I3 in the upper part of said hollow valve rod. 5 are closed by the upper valve rod guide H3 in the lowermost position of said jolt piston 3 and squeeze plunger 2. The exhaust ports [nl in said squeeze plunger 2 are closed by said jolt piston 3 in the latters lowermost position. Said abutment I5 on said hollow valve rod 6 serves as end stop for the maximum length of the pressing stroke of said squeeze plunger 2. Conduit il leads from the bottom 'i' of said squeeze cylinder I into said control valve body 8.

Inside of said jolt piston 3 and adjacent to the lower end of said valve rod guide IG is provided a valve chamber 35 in which the valve it with its valve sleeve i9 is pressed downwards into the closed position by means of the spring 2l. The valve sleeve I9 is slideable on said hollow valve rod The lower face of said valve sleeve I9 rests on the bottom of the bore oi said squeeze plunger 2. The lower portion of the jolt piston S formingr the recess 35 may consist 0f a separate bushing (not shown) to faciliate the insertion of the valve sleeve IS. Between the outside diameter of the valve sleeve I9 and the lowerrnost bore of said jolt piston 3 is the annular space 2l! for the passage of air. Overflow conduit 255 leads from the lower portion of said soueeze cylinder I at a certain height above the bottom I into the valve body 8.

In the molding machine standard 22 which in Fig. 1 is only indicated by fragments is rigidly secured the drawing plunger 23 on which is vertically slideable the drawing cylinder 2li. Conduit 25 leads from the upper end of said drawing cylinder 24 to the control valve body 8.` Rigidly connected with the drawing cylinder 24 are means for supporting the mold lifting pins which serve for lifting the mold rom the pattern onv the molding machine table 4; these parts are not shown in Fig. l.

The supply oi compressed air for the various operations on a molding machine of. the described tyne is controlled by a common control valve, consisting of the control valve body E with the various ports 251, 3d and 3i, the supply con duit 2.?, the exhaust conduit 28 and said conduits I'I, 25 and 25.

Fig. 2 shows the control valve disk 32 with the control valve axle 33 and the operati-ng lever 34. Said control valve disk 32 is placed inside of the control valve body 8 and each of the indicated positions of the partial rotations of the operating lever 34 corresponds to one of the operations in the sequence or the molding process on a molding machine of the above described type. Twelve partial rotations of the operating lever 35 are equal to two complete operating cycles.

Fig. 3 illustrates details of an alternative design of the upper valve rod guide in the jolt piston. The jolt piston 3' has a bore 42 larger in diameter than the flange 4U of the guide sleeve Il which serves for opening and closing the openings I3 in the hollow valve rod 3. The liange @3 rests between two rubber rings 43. A washer 1M isV put on top of the upper rubber ring 43 and the whole arrangement is tightenedl by means of ring nut 45. The inside diameters of the rubber rings 43, of the washer 44 and of the ring nut 45 are larger than the outside diameter ofthe sleeve 4I. By this arrangement it is possible to obtain an air-tight connection in axial direction and at the same time possibilities for radial adjustments between the various moving parts.

Thus the construction of Fig. 3 relates to an adjustable valve rod guide which is so constructed that in the position of rest, namely, when the squeeze plunger and the jolt piston are located in their lowermost positions, the guide sleeve l covers the openings I3 and thus prevents air passing from the valve rod into the chamber 35. During the jolting compressed air can pass from the openings I 3 into the chamber V35 only when an air cushion is formed. The spring 2| of Fig. 3 has the same function as the spring 2l of Fig. 1, namely, it presses the valve downwardly.

A similar design of a valve rod guide may be used in place of the lower valve rod guide 9 in Fig. 1 in the lower part of the squeeze plunger 2.

Ille operation of producing or forming a mold may be briefly described as follows:

In the starting position of the molding machine the squeeze plunger 2 rests in its lowermost position; i. e. on the bottom l of the squeeze cylinder I and the openings I I in' the hollow valve rod 3 communicate with the passages I2 in the lower part of the squeeze plunger 2, whereas the openings I3are closed by the upper'valve rod guide Ill in the jolt piston 3.

To initiate the jolting operation the operating lever 34 of the control valve disk 32 is turned to one of the positions marked with I. In this position the conduit 26 is connected with the exhaust conduit 28 and compressed air enters from the'supply conduit 21 into port 29, conduit and then into the hollow valve rod 6. Because of the lowermost position of the squeeze plunger 2 and the jolt piston 3 the upper openings I3 remain closed and the air can only enter through the openings I I into the passages I2 and below the squeeze plunger 2. Now the squeeze plunger 2 begins to ascend together with the jolt piston 3 and it ascends until the openings rests on the bottom of the bore of the squeeze plunger 2 and thus keeps the jolt valve I8 open. Air enters through the annular space below the jolt piston 3 which now commences to ascend.

During this ascending movement of the jolt pismosphere.

II. are closed by the lower cylindrical bore in the squeeze plunger 2. vShortly before the termination of this ascending movement of the squeeze plunger 2 and the joltl piston 3, the air openings I3 in the hollow valve rod 6, which so far had beenvclosed by the valve rod guide I0, are c-pened and the air can enter into the valve chamber 35. Since the jolt piston 3 stays in its lowermost position inside of the squeeze 'plunger 2 the.l lower end of the valve sleeve I9 Due to the weights of the jolt piston 3, of the molding machine table 4 and of the pattern and Vmold (-the latter parts are not shown in Fig.

1 the jolt piston 3 falls downwardly inside of the press plunger 2 and the shock is absorbed by the air cushion which previously had been built up between the squeeze plunger 2 and the bottom I of the press cylinder I.

Due to the unavoidable air leaks between the various sliding parts, additional air might enter the space of the air cushion. If this happens, then the squeeze plunger keeps on ascending until the maximum allowable height of this air cushion for the jolting operation is reached. The overflow conduit 2B serves for exhausting the excess of air through exhaust conduitk 28 into the atmosphere and thus limits the height of the air cushion.

When the jolting operation is completed, the operating lever 34 is turned to the next position in the sequence of the molding operations. In doing so the conduit 5 is connected with the exhaust conduit 28, and the jolt piston 3, as well as the squeeze plunger 2, descend to their lowermost positions. At the same time, the overow conduit 26 is closed in the valve body 8, since it has served its purpose.

To initiate the squeezing operation the operating lever 34 is turned to one of the positions marked ywith II. The overflow conduit 26 remains closed and compressed air from the Supply conduit 2l enters into port 30 and conduit I1 into the space between the squeezel plunger 2 and the bottom 'I of the squeeze cylinder I. The squeeze plunger 2, together with the jolt piston 3, begin to ascend to carry out the squeezing operation. If for some reason the squeeze movement is carried out with the press plate not being in its proper position, then the abutment I6 at the upper end of the hollow valve rod 6 acts as an end stop for the jolt piston and squeeze piston.

When the squeezing operation is completed the operating lever 34 is turned to the next position for connecting the conduit i! with the exhaust conduit 28, whereupon the squeeze plunger 2 descends to its lowermost position. Conduit 26 remains closed.

For the next molding operation. which comprises the drawing of the mold, the operating lever 34. is turned to one of the positions marked with III. Compressed air enters from the supply conduit 21 through port 3| and conduit 25 into the upper end of the drawing cylinder 2e which is lled with oil. The conduit 25 remains closed. With the drawing cylinder 2l! ascending, the mold is lifted oi the pattern on the molding machine table 4; these parts are not shown in Fig. 1. 1

When the drawing operation is completed, which means that the mold has been taken away from the lifting pins, the operating lever is turned to the next position where conduit .25 is connected with the exhaust conduit 28. The drawing cylinder 2 with the liiting pins and their supporting means descend now and the molding machine returns to its initial position. The cycle of the Various molding operations is complete.

The valve rod guide shown in Figure 3 operaies as follows:

Radial movements of the valve rod 6 are absorbed by the rubber rings 43. These radial movements are possible since the outer diameter of the guide sleeve 4| is smaller than the face oi the jolt piston 3 at its lower end and is also smaller than the washer 44 and the ring nut 45. Furthermore, there is a space between the bore #2 and the outer surfaces of the flange 40.

The utilization of this novel valve rod guide increases the safety in the operation of the jolt and squeeze plungers considerably. The combination of the overflow conduit with a suitable control valve assures a regularly working air cushion which is independent of the weight and form of the flask and also to a great extent independent of the air pressure in the air supply conduit.

I claim:

l. A molding machine with shockless jolting, comprising a squeeze cylinder, a hollow squeeze plunger reciprocable within said cylinder and having a recess formed at the bottom thereof, a jolt piston reciprocably mounted in said squeeze plunger and reciprocable along with said plunger, a hollow valve rod immovably mounted in said cylinder and extending through said squeeze plunger and said jolt piston, said valve rod having upper openings formed therein, said upper openings of the valve rod communicating with said recesses of the jolt piston in the upper position of said plunger, said valve rod further having lower openings formed therein, recesses formed in the bottom of said squeeze plunger, said lower openings of the valve rod communicating with said recesses in the bottom of the squeeze plunger in the lower position of the plunger, a conduit connected with said valve rod for supplying compressed air thereto, the compressed air entering the recesses of the plunger through the lower openings and raising said squeeze plunger and forming a cushion at the bottom of said squeeze cylinder at the beginning of the jolting operation, said plunger while being raised closing said lower openings and connecting said upper openings with the recesses of said jolt piston to commence the actual jolting operation, an overflow conduit communicating with the interior of said cylinder at a height above the bottom thereof and below said squeeze plunger in the upper position of the latter, and a control valve connected with the first-mentioned conduit and with said overflow conduit and having means connecting said overflow conduit with the atmosphere during the jolting operation to exhaust any possible excess of air after having built up the necessary height of the air cushion.

2. A molding machine according to claim l, characterized in that the jolt piston contains a valve chamber ormed at the lower end thereof, and in said valve chamber, slidable on said hollow valve rod, a valve sleeve, and means maintaining open said valve sleeve when the lower end of said valve sleeve rests on the squeeze plunger.

3. A molding machine according to claim 1, comprising guiding means for the hollow valve rod in the jolt piston and in the squeeze plunger, said guiding means consisting of guide sleeves which permit radial adjustments and at the same time secure an axially air-tight connection between the hollow valve rod and the squeeze plunger and the jolt piston.

HANS JAKOB ROTHSCHILD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,157,403 Lewis Oct. 19, 1915 1,642,074 Lewis Sept. 13, 1927 FOREIGN PATENTS Number Country Date 473,794 Germany Apr. 3, 1929 583,389 Germany Sept. 2, 1933 

